WO2002033362A1

WO2002033362A1 - Flow sensor

Info

Publication number: WO2002033362A1
Application number: PCT/JP2001/009119
Authority: WO
Inventors: Shoji Kamiunten; Yoshiyuki Ishikura; Shinichi Ike; Seiichiro Kinugasa; Hidekazu Tanaka
Original assignee: Yamatake Corporation
Priority date: 2000-10-17
Filing date: 2001-10-17
Publication date: 2002-04-25
Also published as: US20040045352A1; US7117736B2; JP3825242B2; EP1333255B1; EP1333255A4; CN1476530A; JP2002122454A; EP1333255A1; CN1231745C

Abstract

A flow sensor (1) comprising a substrate (4) having surface (4a) side facing a channel (3) of fluid (2) to be measured, and a channel forming member (5) and a plate (6) disposed oppositely across the substrate (4). The substrate (4) is formed of a stainless plate having thickness on the order of 50-150 νm and an electric insulating film is formed on the side (4b) opposite to the channel (3) side. A temperature sensor (7) for measuring the current velocity (flow rate) of the fluid (2) an ambient termperature sensor (8), an electrode pad (9) and a thin metal film (10) for wiring are foremd thereon.

Description

Description One sensor Background of the invention

The present invention relates to a flow sensor for measuring a flow velocity or a flow rate of a fluid flowing in a flow path, particularly to a thermal flow sensor.

Two evening eves are known as thermal flow sensors that measure the flow rate and flow velocity of a fluid. The first type is a type (indirect heat type) in which the spatial temperature distribution of the fluid due to the heat generated from the heating element (heater) causes a bias due to the flow, and this is detected by a temperature sensor. The second type is a self-heating type that detects a change in electric power or a change in resistance due to removal of heat from a heating element by a fluid, and detects a flow velocity or a flow rate (self-heating type). In the past, this type of flow sensor was mainly used for non-corrosive gases, but recently a sensor that can be used for liquids and corrosive gases has been developed. For example, as one example, a flow sensor disclosed in Japanese Patent Application Laid-Open No. Hei 4-295572 (prior art 1) is known. Also, a thermistor flow rate sensor and a liquid flow rate sensor (prior art 2) disclosed in Japanese Patent Application Laid-Open No. 8-146600 are known.

In the flow sensor described in Prior Art 1, first, second, and third regions are provided on the first surface of the silicon substrate. A heating element is provided in the first area, a thermometer component is provided in the second area, and the first and second areas are insulated from each other by a porous silicon area obtained by oxidizing the third area. . A second surface opposite to the first surface is a surface that receives a fluid flow. In addition, a silicon cap is fixed to the first surface to increase the rigidity of the silicon base and protect the heating element and thermometer components. In the flow velocity and flow rate sensor described in Prior Art 2, a heating element and its electrodes are formed on one surface of a plate-like substrate such as alumina or Si ₂ , and the heating element is covered with an insulator. A thermistor for measuring the temperature of the heating element and its electrode are formed on this insulator, and the opposite surface is fixed to the inner surface of the force par (container) with an adhesive so that the sensor is completely separated from the fluid. Be isolated. The cover has good thermal conductivity and is made of a metal having good corrosion resistance to the fluid to be measured, for example, stainless steel (SUS316L). Therefore, there is no problem such as abrasion and corrosion as compared with the flow sensor of the prior art 1 described above, and the reliability can be improved.

However, the flow rate sensor described in Prior Art 1 has a problem that it cannot be used for corrosive gases or liquids used in semiconductor manufacturing equipment, etc., because the silicon base is directly exposed to the fluid. . In the flow velocity and flow rate sensor described in Prior Art 2, since the sensor is fixed to the inner surface of the cover with an adhesive, the heat transfer efficiency between the fluid and the sensor decreases, the heat capacity of the sensor increases, and the sensitivity increases. And the response speed is reduced. Another problem was that the characteristics varied depending on the amount of adhesive used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a flow sensor capable of handling almost corrosive fluids and improving responsiveness and sensitivity. It is to provide Summary of the Invention

The flow sensor according to the present invention includes a thin plate-shaped substrate forming a part of a fluid flow path, and a temperature detection unit including a heating element provided on a surface of the substrate opposite to the flow path side. Is done. According to this configuration, since the temperature detecting means including the heating element is provided on the surface of the substrate opposite to the flow path side, The fluid does not come into direct contact with the temperature detection means and can be used for measuring corrosive gases and liquids depending on the material of the substrate. Since the temperature detection means is not exposed to fluid, it is unlikely to accumulate dirt or change over time due to fluid, and maintains stable performance. Since the substrate is a thin plate, heat conduction between the fluid and the temperature detecting means is good. BRIEF DESCRIPTION OF THE FIGURES

1A, 1B, and 1C are a front view, a cross-sectional view, and a rear view showing one embodiment of a flow sensor according to the present invention.

FIG. 2 is a front view of the sensor unit.

FIG. 3 is a front view showing another embodiment of the sensor unit.

FIG. 4 is a front view showing another embodiment of the sensor unit.

FIG. 5 is a front view showing another embodiment of the sensor unit.

FIG. 6 is a front view showing another embodiment of the sensor unit.

FIG. 7 is a front view showing another embodiment of the sensor unit.

8A, 8B, and 8C are a front view, a sectional view, and a rear view showing another embodiment of the present invention.

FIG. 9 is a diagram showing the relationship between the distance and the temperature difference between the two temperature sensors when the distance from the heating element of the upstream and downstream temperature sensors is changed.

FIG. 10 is a diagram showing the distance from the heater (R h) to the temperature sensors (R u, R d).

FIG. 11 is a diagram showing a constant temperature difference circuit.

FIG. 12 is a diagram showing another constant temperature difference circuit.

FIG. 13 is a diagram showing another constant temperature difference circuit.

FIG. 14 is a diagram showing a sensor output circuit.

FIG. 15 is a diagram showing another sensor output circuit. Detailed description of the embodiment

Hereinafter, the present invention will be described in detail with reference to the drawings.

1A, 1B, and 1C are a front view, a cross-sectional view, and a rear view showing an embodiment of a flow sensor according to the present invention, and FIG. 2 is a front view of a sensor unit. In these figures, the flow sensor 1 is disposed so that the surface 4 a faces the substrate 4 facing the flow path 3 of the fluid to be measured (hereinafter referred to as fluid) 2 with the substrate 4 interposed therebetween. It is composed of a flow path forming member 5 and a plate 6. The substrate 4 and the flow path forming member 5 form a part of the flow path 3. The flow path forming member 5 and the plate 6 are joined by welding, brazing, porting, or the like.

The substrate 4 is formed in an elongated rectangular thin plate shape, and the outer peripheral edge is joined to the back surface of the flow path forming member 5. As a material of the substrate 4, a material having low thermal conductivity, high heat resistance, corrosion resistance and high rigidity is preferable. In the present embodiment, the sensor portion 4A having a diaphragm structure is formed of a thin stainless steel plate having a thickness of about 50 to 150 m, and a central portion thereof is separated from the plate 6 and thermally insulated. To form When the substrate 4 is made of stainless steel, if the plate thickness is 50 m or less, the strength decreases, which is not preferable. If it is more than 150 / zm, the heat transfer efficiency in the thickness direction of the substrate, that is, the heat transfer efficiency between the fluid and the temperature detecting means decreases, and the amount of heat transfer in the direction parallel to the surface of the substrate (heat loss). Undesirably increases.

An electrical insulating film (not shown) is formed on the back surface 4 b of the sensor unit 4 A opposite to the passage 3 side, and a temperature detection sensor for measuring the flow rate (flow rate) of the fluid 2 is formed thereon. (Temperature detecting means) 7, ambient temperature sensor 8, electrode pad 9, and metal thin film 10 for wiring are formed by a known thin film forming technique. For example, it is formed by depositing a material such as platinum on the surface of the electrical insulating film and etching it into a predetermined pattern. The ambient temperature sensor 8 is electrically connected to the electrode pad 9 via the wiring metal thin film 10.

The temperature detection sensor 7 is formed at the center of the back surface of the sensor section 4A. The ambient temperature sensor 8 is used to compensate for the change in the ambient temperature, that is, the fluid temperature, and is formed near the outer peripheral edge of the back surface of the sensor section 4A. As the electric insulating film, for example, a thin silicon oxide (Si ₂ ) film or a silicon nitride film having a thickness of about several thousand angstroms is used. The silicon oxide film is formed by, for example, sputtering, CVD, or applying a solvent mixed with silicon oxide and heating it to a predetermined temperature to melt and solidify the silicon oxide. The silicon nitride film is formed by sputtering or CVD. The ambient temperature sensor 8 may be provided outside the sensor section 4 A on the substrate 4 or in a portion other than the substrate 4. Also, the electrode pad 9 may be provided on the substrate 4 outside the sensor section 4A, and the electrode may be taken out therefrom.

In general, the configuration of the temperature detection sensor 7 for measuring the flow velocity (flow rate) is as follows.

I) One heating element and temperature sensor,

Π) Two heating elements and temperature sensors,

Π) Heating element / temperature sensor and temperature sensor

There are three possibilities.

FIG. 2 shows an example in which one heating element 11 constitutes a self-heating type temperature detection sensor 7. One ambient temperature sensor 8 is provided on the upstream side near the outer peripheral portion of the back surface of the sensor section 4A.

FIG. 3 shows an example in which a self-heating type temperature detecting sensor 7 is composed of two heating elements 11A and 11B. The two heating elements 11 A and 11 B are arranged close to the center of the back surface of the sensor section 4 A in the flow direction of the fluid 2. Also, two ambient temperature sensors 8A and 8B are provided. These ambient temperature sensors The sensors 8A and 8B are formed near the outer periphery of the sensor unit 4A so as to face each other in a direction orthogonal to the flow direction of the fluid 2.

FIG. 4 shows an example in which one heating element 11 and two temperature sensors 12 A and 12 B constitute an indirectly heated temperature detection sensor 7. The heating element 11 is provided at the center of the back surface of the sensor section 4A. The two temperature sensors 12 A and 12 B are respectively arranged on the upstream side and the downstream side in the flow direction of the fluid 2 with the heating element 11 interposed therebetween. Further, one ambient temperature sensor 8 is provided on the outer peripheral portion of the back surface of the sensor section 4A, on the upstream side in the flow direction of the fluid 2. The pattern width of the heating element 11 is preferably 10 to 50 m, and the pattern width of the temperature sensors 12 A and 12 B and the ambient temperature sensor 8 is preferably about 5 to 10 m.

FIG. 5 shows an example in which a self-heating type temperature detecting sensor 7 is composed of two heating elements 11A and 11B. The two heating elements 11A and 1IB are arranged close to the center of the back surface of the sensor section 4A in the flow direction of the fluid 2. Also, one ambient temperature sensor 8 is provided on the upstream side in the flow direction of the fluid 2.

Fig. 6 shows an example in which two heating elements 11A and 11B are arranged close to the center of the back surface of the sensor section 4A in the flow direction of the fluid 2 to form a self-heating type temperature detection sensor 7. . Two ambient temperature sensors 8A and 8B are provided on the upstream and downstream sides in the flow direction of the fluid 2 near the outer periphery of the back surface of the sensor section 4A.

Fig. 7 shows an example in which two heating elements 11A and 11B are arranged close to the center of the back surface of the sensor section 4A in the flow direction of the fluid 2 to form a self-heating type temperature detection sensor 7. Is shown. One ambient temperature sensor 8 is provided on the back surface of the sensor unit 4A near the outer periphery in a direction orthogonal to the flow direction of the fluid 2. In FIG. 1, the flow path forming member 5 is made of an elongated metal plate, and a concave portion 14 slightly smaller than the substrate 4 and having a depth of about 0.5 to several mm is formed at the center of the rear surface. The space formed between the recess 14 and the surface 4 a of the substrate 4 forms a part of the flow path 3 of the fluid 2. The longitudinal direction of the flow path forming member 5 Near both ends, fluid supply port 15 and fluid discharge port communicating with flow path 3

16 are formed through.

The plate 6 is made of an elongated metal plate, and is closely attached to and bonded to the back surface 4 b of the substrate 4. In the center of the plate 6, a through hole 17 having substantially the same size as the sensor portion 4A of the substrate 4 is provided.

An electrode 18 for electrically connecting the 7 and the ambient temperature sensor 8 to the outside is provided. The electrode 18 is formed by fixing a plurality of metal pins 20 to a metal frame 19 via an octagonal glass 21.

The inner end of 0 is joined to the electrode pad 9 of the sensor section 4A by brazing.

When mounting the electrode 18, it is preferable that the through hole 17 is evacuated and mounted, or a dry inert gas having low thermal conductivity is sealed in the closed space between the substrate 4 and the electrode 18. However, it can be open to the atmosphere if it is not affected by the surrounding wind. Instead of using the electrode 18, the electrode pad of the sensor and the external circuit board may be connected with a wire pound made of a gold wire.

The material of the flow path forming member 5 is preferably a material having high thermal conductivity and high heat resistance, corrosion resistance and rigidity because it also serves as a structural material and a heat sink. In order to apply the flow sensor 1 to a corrosive fluid, it is preferable that all parts in contact with the fluid 2 are made of the same material having corrosion resistance. It is preferable to carry out without. For this reason, in this embodiment, the flow path forming member 5 is formed of stainless steel (particularly, SUS316L), which is the same material as the substrate 4. In this way, by forming the substrate 4 and the flow path forming member 5 from stainless steel, it is possible to perform joining without using a dissimilar metal by using a YAG laser or welding.

Stainless steel has relatively good workability and is used as a sensor material. It is suitable. However, not only stainless steel, but also materials with high thermal conductivity, such as sapphire and ceramics, can be used because if they are formed thinner, the escape of heat to the surface can be reduced. The thermal conductivity of stainless steel, sapphire, and ceramics at 300 K is about 16, 46, and 36 [WZ m K], respectively, depending on the composition.

As a material of the plate 6, a material having high thermal conductivity, heat resistance, and rigidity is also preferable because it also serves as a structural material and a heat sink, but since it does not come into contact with the measurement fluid, corrosion resistance is not so necessary.

In the flow sensor 1 shown in FIG. 2 using one heating element 11 1, the flow velocity can be converted into a voltage signal by using a constant temperature difference circuit as shown in FIG.

As shown in Fig. 11, this constant temperature difference circuit consists of a series circuit of resistors R 1 and R 2, a heating element (resistance heater) 11, a resistor R 3, and an ambient temperature sensor 8. A circuit and an operational amplifier OP1 having a connection point voltage of the resistor R1 and the heating element 11 as an inverting input and a non-inverting input of a connection point voltage of the resistor R2 and the resistor R3. The output of the operational amplifier OP 1 is connected to one end of the resistors R 1 and R 2 that constitute the bridge circuit. The resistance values of the resistors R 1, R 2, and R 3 are set such that the temperature is always higher than the ambient temperature sensor 8 by a constant temperature.

In such a circuit configuration, when the fluid 2 flows in the direction of the arrow, heat is removed from the heating element 11 by the fluid 2 and the resistance value of the heating element 11 decreases, so that the equilibrium state of the bridge circuit is broken. As a result, a voltage corresponding to the difference voltage generated between the inverting and non-inverting inputs of the operational amplifier OP 1 is applied from the operational amplifier 0 P 1 to the bridge circuit, and the heating element 11 is compensated for the heat taken by the fluid 2. Increase the calorific value. As a result, the bridge circuit returns to an equilibrium state by increasing the resistance value of the heating element 11. But Therefore, a voltage corresponding to the flow velocity is applied to the bridge circuit in the equilibrium state. The constant temperature difference circuit in FIG. 11 outputs, as a voltage output, the voltage between the terminals of the heating element 11 among the voltages applied to the bridge circuit at this time.

In this way, the constant temperature difference circuit controls the current or voltage so that the temperature of the heating element 11 becomes constant temperature higher than the ambient temperature measured by the ambient temperature sensor 8, thereby keeping the temperature difference constant. By detecting a change in current or power, the flow velocity or flow rate of fluid 2 can be measured.

3 and 6 combine two flow sensors shown in FIG. In such a configuration, the circuit shown in Fig. 13 detects the voltage difference between the heating element 11A on the upstream side and the heating element 11B on the downstream side to determine the flow velocity or flow rate of the fluid 2 and the direction of the flow. Can be measured. The circuit shown in Fig. 13 uses the two constant temperature difference circuits shown in Fig. 11 to amplify the voltage difference between the terminals of the heating elements 11A and 11B with the operational amplifier OP3 and output the voltage. It shall be. The magnitude of the voltage output indicates the flow velocity, and the polarity indicates the direction. Although the voltage difference is used, the current or power difference may be used.

5 and 7 using two heating elements 11A and 11B to detect the flow velocity and flow direction of the fluid using the constant temperature difference circuit shown in Fig. 12. can do. The circuit shown in Fig. 12 is composed of a bridge circuit composed of resistors R1, R2, a heating element (resistance heater), 11A, 11B, a resistor R3, and an ambient temperature sensor 8. It is similar to the constant temperature difference circuit shown in Fig. 11 in that it includes an operational amplifier OP1 that keeps the bridge circuit in a balanced state. In the circuit shown in Fig. 12, the operational amplifiers 増幅 P2A and OP2B, which amplify the voltage between the terminals of two heating elements 11A and 11B connected in series, respectively, and the difference between these outputs An OP 3 is provided as an input, and the output of the OP 3 Voltage output.

When the two heating elements 11A and 11B are made into one heating element by energizing the bridge circuit of the constant temperature difference circuit shown in Fig. 12, and heated to a certain higher temperature than the ambient temperature When the fluid 2 flows in the direction of the arrow, the heating element 11 A located on the upstream side is cooled and its temperature drops. On the other hand, the heating element 11 B located on the downstream side rises in temperature due to heat conduction from the heating element 11 A on the upstream side using the flow of the fluid 2 as a medium, and the two heating elements 11 A, 11 B A temperature difference occurs between the two. This temperature difference can be considered as a change in the resistance values of the heating elements 11A and 11B. By detecting the change in the resistance value or the voltage between both terminals and outputting the sensor output, the flow velocity or flow rate of the fluid 2 is measured. ,

In this case, when the temperature difference is detected using the two heating elements 11A and 11B, the reproducibility and accuracy can be improved as compared with the case where one is used. In addition, the flow direction of the fluid 2 can be detected by the resistance change of the heating elements 11A and 1IB.

In the flow sensor shown in Fig. 4 that uses one heating element 11 and two temperature sensors 12A and 12B, the heating element is energized by energizing a constant temperature difference circuit as shown in Fig. 11. When fluid 2 flows in the direction of the arrow while heating 1 1 to a certain higher temperature than the ambient temperature, the temperature between the upstream temperature sensor 12 A and the downstream temperature sensor 12 B of the heating element 11 will increase. A temperature difference occurs. Therefore, the flow rate or flow rate of the fluid 2 is measured by detecting the voltage difference or the resistance value difference by the circuit shown in FIG. 14 or FIG.

The circuit shown in FIG. 14 supplies a voltage output using a bridge circuit including two temperature sensors 12A and 12B. In the circuit shown in Fig. 15, the voltage between the terminals of two temperature sensors 12 A and 12 B connected in series is amplified by operational amplifiers 〇 P 1 and OP 2 respectively, and the difference is further amplified by operational amplifier OP The voltage amplified in step 3 is used as the voltage output. In this case, two temperature sensors 1

Since 2A and 12B are used, the direction of the flow of fluid 2 can be detected, and this configuration has the highest accuracy and reproducibility.

In such a flow sensor 1, the temperature detection sensor 7 is provided on the surface of the substrate 4 made of a thin plate-shaped body opposite to the surface in contact with the fluid 2. For this reason, the temperature detection sensor 7, the ambient temperature sensor 8, the electrode pad 9, and the like do not directly contact the fluid 2 to be corroded or deteriorated, and no dust or the like is attached. As a result, it can be used for measuring corrosive gases and liquids used in semiconductor manufacturing equipment and the like, and the reliability and durability of the sensor can be improved.

Further, since the substrate 4 is formed of a thin plate made of stainless steel having a low thermal conductivity, the heat conduction in a direction parallel to the surface is small, and the thickness direction of the substrate, that is, the fluid 2 and the temperature detection sensor 7 are formed. Good heat conduction between them, and can improve responsiveness. Stainless steel is excellent in heat resistance, corrosion resistance, workability and rigidity, and is suitable as a sensor material.

8A, 8B, and 8C are a front view, a cross-sectional view, and a rear view showing another embodiment of the present invention. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the present embodiment, a sensor mounting hole 31 is formed in the flow path forming member 30 forming the flow path 3 of the fluid 2, and a flow sensor 32 is mounted in the sensor mounting hole 31. The flow path forming member 30 is formed of stainless steel. The flow sensor 32 has a circular opening 33 in the center of the front surface, an open back surface, and a flange-shaped package provided with a flange 34 at the rear end of the outer peripheral surface.

3 and a substrate 4 whose outer peripheral portion is joined to the front surface of the package 35 to cover the opening 33. The substrate 4 is formed of a thin plate made of stainless steel, and a temperature detecting sensor 7, an ambient temperature sensor 8, an electrode pad 9, and a metal thin film 10 for wiring shown in FIG. It is provided via an edge film.

The substrate 4 is not limited to a square, but may be another shape such as a circle. The configurations of the temperature detection sensor 7 and the ambient temperature sensor 8 are not limited to those shown in FIG. 4, but may be those shown in FIG. 2, FIG. 3, FIG. 5, FIG. 6, or FIG. . Further, the ambient temperature sensor 8 may be provided in a portion other than the substrate 4.

The package 35 is made of stainless steel, is fitted into the sensor mounting hole 31 of the flow path forming member 30, and the flange 34 is joined to the back surface of the flow path forming member 30 by YAG laser welding or the like. The front surface of the package 35 and the surface of the substrate 4 form the same plane as the inner wall surface 30 a of the flow path forming member 30 and constitute a part of the flow path 3. An electrode 18 is incorporated into the package 35 from the opening on the back side, and the pin 20 is connected to the electrode pad 9 by brazing. Note that the sensor electrode pad may be connected to the circuit board by a single wire bond made of gold wire.

In the flow sensor 32 having such a structure, the sensor mounting hole 31 is formed in the flow path forming member 30, and the flow sensor 32 is fitted into the sensor mounting hole 31, and the surface of the substrate 4 is fluidized. Touch 2 For this reason, since it is only necessary to join the package 35 to the flow path forming member 30, there is no need to use a special device, component, or the like, and the mounting can be easily performed. The flange 34 and the flow path forming member 30 may be joined by a port using a sealing material such as a ring.

In FIG. 9, the temperature of the heating element 11 is set 30 ° C. higher than the ambient temperature in the air in the structure of the sensor section 4 A shown in FIG. 4, and the upstream and downstream temperature sensors 12 A, The relationship between the distance and the temperature difference between the two temperature sensors 12A and 12B when the simulation is performed by changing the distance of the 12B from the heating element 11 is shown. Figure 10 shows the distance from the heater Rh (heating element) to the temperature sensors (Ru, Rd). As evident from Figure 9 In this condition, the position where the temperature difference becomes the largest under these conditions was a position of 650 m from the center of the heating element 11 respectively.

As described above, according to the present invention, since the temperature detecting means including the heating element is provided on the surface of the substrate made of a thin plate-like body forming a part of the flow path on the side opposite to the flow path side, the fluid Does not come into direct contact with temperature detecting means, electrode pads, metal thin films for wiring, etc. Therefore, by selecting the material of the substrate, it is possible to measure a liquid or a corrosive gas, and a highly reliable and durable sensor can be provided.

Examples of the material of the substrate include stainless steel, sapphire, ceramics and the like. Among them, stainless steel is particularly suitable in terms of corrosion resistance, workability, thermal conductivity, and rigidity. Sapphire is preferred if needed.

The thickness of the substrate is preferably as thin as possible in order to improve the heat conduction between the fluid and the temperature detecting means and to reduce the lateral heat conduction in the substrate. However, the conditions need to be determined in consideration of external factors in manufacturing such as workability, strength, and handling. Therefore, in the case of stainless steel, about 50 to 150 m is optimal.

Further, according to the invention, since a part of the flow path can be configured as a mouthpiece sensor, the flow rate can be measured only by incorporating the sensor into the flow path. Thereby, the bonding of the thin plate-shaped substrate is performed stably, and the reliability is improved. Also, since the flow path can be formed small and with high accuracy in accordance with the measurement range, etc., a sensor for high accuracy or low flow rate can be realized.

Further, according to the present invention, an opening is provided on the front surface which comes into contact with the fluid while facing the inside of the flow path of the package attached to the sensor mounting hole provided in the flow path forming member for forming the flow path of the fluid. Is covered by a thin plate-shaped substrate, and a temperature detecting means including a heating element is provided on the surface of the substrate opposite to the flow path side, so no special equipment, parts, etc. are required, and the flow path forming member is simple. To Can be attached.

Claims

The scope of the claims

1. A thin plate-shaped substrate forming a part of a fluid flow path, and a temperature detecting means including a heating element provided on a surface of the substrate opposite to the flow path side. Flow sensor.

2. The flow sensor according to claim 1, wherein the substrate and the flow path forming member are formed of any one of stainless steel, sapphire, and ceramics.

3. The flow sensor according to claim 1, wherein the substrate is formed of stainless steel having a thickness of 50 to 150 m.

4. A flow path forming member that constitutes a flow path of the fluid and has an opening in the middle of the flow path, a thin plate-shaped substrate that covers the opening of the flow path forming member, and a flow path side of the base plate. And a temperature detecting means including a heating element provided on the opposite surface.

5. The flow sensor according to claim 4, wherein the substrate and the flow path forming member are formed of any one of stainless steel, sapphire, and ceramics.

6. The flow sensor according to claim 4, wherein the substrate is formed of stainless steel having a thickness of 50 to 15 O ^ m.

7. A package is provided to be mounted in a sensor mounting hole provided in a flow path forming member for forming a flow path of a fluid, and an opening is provided in a front surface of the package which faces the fluid and is in contact with the fluid. A flow sensor, comprising: a thin plate-shaped substrate; and a temperature detection unit including a heating element provided on a surface of the substrate opposite to a channel side.

8. The flow sensor according to claim 7, wherein the substrate and the flow path forming member are formed of any one of stainless steel, sapphire, and ceramics.

9. The substrate is made of stainless steel with a thickness of 50 to 15 Om The flow sensor according to claim 7, wherein